System and method for monitoring physiological parameters

ABSTRACT

Methods and apparatus are provided for generating a continuous audible indication of a physiological parameter such as human skin resistivity and the like, suitable either for comparison with a preselected calibration value or for correlation with a functionally related other physiological parameter.

United States Patent 11 1 1111 3,924,606

Silva et al. Dec. 9, 1975 [54] Y TE AND METHOD FOR MONITORING 2,918,05412/1959 0660mm 128/205 T PHYSIOLOGICAL PARAMETERS 3,316,897 5/1967Weidinger 128/206 R 3,453,546 7/1969 Fryer 128/2.l A

[ 1 Inventors: Jo Silva; J Narrace, 3,456,212 7/1969 Partridge....128/2.05 T both of Laredo, Tex. 3,495,596 2/1970 Condict l28/2.1 B

. 3,513,832 5/1970 Klemm et a1... 128/205 R [73] Assgnee' Lamb 3,603,8819/1971 Thornton 128/21 A [22] i No 23 1973 7 3,648,686 3/1972 Payne128/2.1 Z

[21] Appl. No.: 418,400

Przmary ExammerW1ll1am E. Kamm Related Appllcatlon Dam Attorney, Agent,or Firm-Bard, Springs, Matthews &

[63] Continuation-impart of Ser. No. 334,743, Feb. 22, k n

1973, Pat. No. 3,875,930.

[52] US. Cl 128/2.1 B; l28/2.l M [57] ABSTRACT 51 E gl Search 128/205 Tx 2 Methods and apparatus are provided for generating a 128/206 R 21 A,21 B, 21 M R 205 continuous audible indication of a physiological pa- P205 R 205 S rameter such as human skm resistivity and the like,

suitable either for comparison with a preselected calibration value orfor correlation with a functionally re- [56] References Cited latedother h siolo 'cal arameter UNlTED STATES PATENTS P y P 2,829,638 4/1958Douglas l28/2.l Z 9Claims, 6 Drawing Figures 4 254 A f a C SINE :VAVE P-::i- -FL12R w L 4 SQUARE WAVE 1I E Y MUTE 1 i SWITCH 1 VT 6 L 5 s k 77L 18 M 19 N 22 TR/GGERE/D Z loEMtiou INTI; u g i CONVERTER N/V/f LJOSCILLATOR 470R [.ATOR GRATOR BRATOR DECK 7 i- -F SPEAKER H "J L WAYSWITCH TRIGGERED OSCILLATOR f SWITCH I SINE WAVE 70 CLAMP SQUARE WAVE n1 D I SUPPLY e27 US. Patent Dec. 9, 1975 Sheet 2 of4 3,924,606

f 3 v G M w H C m 5 H 3 :5 7 3 A V 3 M, W a v, W 0 (CPL 2s 2 m Q fb/b/ELIL 2 R .0 D R DR 6 WM Em %m H 0 R mm. m m w FWO W TO POWER SUPPLY TO LPFILTER OSCILLATOR US. Patent Dec. 9, 1975 Sheet 3 of4 3,924,606

F MAM/\ J\MWl MAM JWVWL J v2 m mumbom 5 3 v ie WEE om W m: V 7 W9 W2 DNNNR N f m mm a T B US. Patent Dec. 9, 1975 m min Related Patents andPatent Applications This is a continuation-in-part of the co-pendingpatents application Ser. No. 334,743, now Pat. No.

3,875,930, which was filed Feb. 22, 1973.

Background of Invention This invention relates to methods and apparatusfor observing physiological parameters of the human body and the likeand, more particularly, relates to methods and apparatus for providing acontinuous audible indication of a selected physiological parametereither for comparison with a preselected calibration value or forcorrelation with a different but functionally related physiologicalparameter.

It is well known that the human brain generates electrical pulsations atfrequencies which are functionally related to mental and physicalcondition, and it is now well known that there are certain definitefrequency ranges wherein the mental activity and capability of a persondiffers to a distinguishable degree. More particularly, the human brainprovides pulsations in the Beta Range (above l4 cps) when a person iswide awake and in a normally active state, and that the frequency is inthe Delta Range (below 4 cps when the person is in a deep sleep or comacondition. When the brain wave frequency drops to zero, of course, theperson is physiologically and mentally dead.

Between these two frequencies is the Alpha Range, wherein the frequencyrate falls between 7-14 cps, and the Theta Range, wherein the rate isbetween 4-7 cps. The existence and significance of these ranges haveonly recently been recognized and are not yet fully understood, since notwo human beings ever react exactly the same. Nevertheless, it is nowclearly apparent that when a persons brainwave frequencies are withinthe Alpha range, a person is often imbued with significantly greaterpowers of concentration and I a deeper inner awareness, and frequentlywith an enhanced capacity for such powers as extrasensoryperception andthe like. Relatively little experimentation has been done with regard tothe Theta range, but subjects have sometimes exhibited extraordinarycapabilities when in that state.

It was previously thought that a persons brain wave frequency is acompletely uncontrollable condition and that a person tends to driftbetween Beta and Delta in an entirely involuntary manner. For thisreason, established scientific and medical opinion has, until recently,tended to look with skepticism on claims advanced on behalf of esotericpractices such as yoga, transcendental meditation, etc. Now, however,conditioning exercises have been devised and made available whereby anexperienced practitioner of otherwise ordinary capacities can shift hisbrain wave frequency rate into the Alpha range to obtain benefits suchas those hereinbefore mentioned. Since these conditioning exercises areformulated and based on accepted scientific theory' rather than on themore philosophical and metaphysiby such exercises are repeatable to amuch greater degree, they are now widely accepted in conventionalscientific circles.

Insofar as the measurement of human brain waves is concerned, it is oldand well known, as evidenced by US. Pat. Nos. 3,662,746 and 3,623,477,to derive an electroencephalographical voltage signal indicative of suchwaves of pulsations. This signal may be visually or even audiblydisplayed, or it may be graphically recorded to provide what ispopularly known as an EEG. Thus, conventional detection and recordingapparatus is used to monitor the subject using the aforementionedconditioning exercises, in order to establish when and if the subjectactually enters the Alpha state. For example, see the December 1972issue of Electronics World, pp. 33-38, and also US. Pat No. 3,548,812,for a fuller discussion of experimentation utilizing such measurements.See also US. Pat. Nos. 2,860,627, 3,662,746 and 3,658,054 for otherdiscussions of conventional apparatus of this type.

The conditioning exercises hereinbefore referred to are comprised of aseries of predetermined mental images which the subject or practitionerfonnulates according to prescribed sequence, and no external agency isactually required as such. Since the practitioner seldom if everexperiences any physical sensation when shifting to the Alpha state,some users of the exercises have practiced the'technique while connectedto electroencephalographic apparatus in order to indicate that the Alphastate has in fact been attained, as indicated in the aforementionedarticle in Electronics World. Further, in some cases theencephalographic signal has been translated into an audio output,whereby the frequency of the signal will inform and, to a limitedextent, guide the practitioner in attaining the Alpha state. Thistechnique is often of advantage in assisting or guiding a practitionerof limited experience and confidence. Nevertheless, the same audiblesignal which assists and guides the practitioner in descending out ofthe Beta range is also a disadvantage when the practitioner approachesand enters the Alpha range. A subject is not in a:hypnotic state when inthe Alpha rangefof course, and is still fully aware of his surroundingsand in complete control of his faculties. Hence, the audible signal canoften be a distraction which impedes rather than assists thepractitioner at the very moment he is at the threshold of the Alpharange.

Because of this disadvantage, it is conventional when utilizing theassistance of the audible representation of the practitioners brain wavefrequency to employ the assistance of another person to monitor thesignal and disconnect it as the practitioner enters the Alpha range.However, this is also undesirable for the obvious reason that theconditioning exercises are designed for self use, and it defeats theentire purpose of the technique if another person is required to be inattendance.

These and other advantages of the prior art are overcomewith the presentinvention, and novel methods and apparatus are herewith provided formonitoring and assisting the user of such conditioning exercises withoutthe aid and attendance of another party.

Summary of Invention In an ideal embodiment of the present invention, aconventional headgear-type assembly of electrodes is provided inconjunction with other conventional circuitryfor generating a train ofelectrical pulses or waves in functional relationship to the electricalpulses which are produced by the brain of the wearer of such electrodes.ln addition, however, means is further included to provide an audibleindication of the rate of such signals can be distinguished, one fromthe other,

however, it is preferable for such purposes that each signal be of adifferent fixed pitch or tone. Accordingly, the frequencycharacteristics of the signals which are of interest will necessarily beof some manifestation other than tone or pitch.

In the ideal embodiment of the present invention, the brain wavemeasurement signal is applied to a triggered oscillator, which isadapted to generate a fixed tone signal, but which interrupts suchsignal upon the receipt of each wave or pulse in the brain wave signal.Hence, the output of the triggered oscillator will be composed of asequence'of discrete tone bursts, and although the frequency of suchbursts is below the normal audio frequency range, the occurrence of suchbursts'will nevertheless be manifested to the subject person.

The second signal source will also produce a similar type of outputsignal, except that the tone of this second signal will be distinctlydifferent from the tone of the first signal, and except that theoccurrence of the tone bursts composing the second signal will be at afixed preselected rate corresponding to the brain wave frequency soughtto be achieved. Thus, it will be clearly apparent when the subjectperson has succeeded in reducing his brain wave frequency to thatrepresented by the rate of occurrence of the tone bursts composing thesecond or monitor signal.

As the practitioner descends through the Beta range, the practitionercan hear the monitor signal decline in frequency and approach that ofthe preselected frequency with which he seeks to relate. In the presentinvention, however, means is also provided whereby both audio outputsignals will become suppressed when they approach frequency coincidence,and whereby such suppression will continue so long as the two signalsremain within a certain preselected range of frequency differences.

As hereinbefore stated, there is an apparent though not fully understoodcorrelation between a persons physiological and phychologicalperformances, and thus it is often useful to measure and observe one ormore such physiological characteristics in conjunction riving a voltagewhich is representative of the skin resis- I tivity of the subjectperson, additional means such as a voltage controlled oscillator toprovide a square wave output having a frequency which is functionallyrelated to such voltage, and finally a fixed tone generator and speakercircuit for deriving an audible indication of such skin resistivity.More particularly, the initial skin resistivity measurement may beobtained by means of a pair ofthumb-press electrodes or the like togenerate the voltage which is used to modulate the aforementionedvoltage controlled oscillator. To this extent, the subject technique andapparatus of the invention parallels the prior art as exemplified by theteachings of US. Pat. No. 3,648,686. To accomplish or provide the secondand third steps or stages of the process or apparatus of the invention,however, the voltage controlled oscillator and fixed tone generator aresubstituted for the variable tone generator utilized in the said US.Pat. No. 3,648,686 to drive the speaker circuit.

It should be noted in this regard that the voltage controlled oscillatorand fixed tone generator are not mere alternatives for the variable tonegenerator, whereby a signal of different form is obtained which is moresuitable to present purposes. What is not readily apparent is that skinresistivity in the average person tends to vary only within relativelynarrow functional limits. This is not a problem in the devices and otherteachings of the prior art; relatively small changes in the frequency ofan audible tone signal are usually clearly discernible by the averagelistener. In the case of the present invention, however, it should benoted that small changes in the rate or frequency at which a fixed tonesignal is interrupted are much more difficult for the average person todetect and evaluate. Thus, in the present invention the voltageamplifier in the initial stage or step is necessarily adapted to providefor much more intensive amplification of the signal originating acrossor between the two thumb-press electrodes, whereby such variations arerendered but more apparent.

But this, in turn, creates a problem with respect to linearity of theoutput signal from the amplifier, which problem did not exist with thecircuits and techniques of the prior art. This problem has beenovercome, however, by the use of a voltage amplifier of improved designwhereby greater linearity of output voltage is provided, as willhereinafter be explained in detail.

It is therefore a feature of the present invention to provide means andmethod for making an audible comparison of one or more selectedphysiological parameters of a human being, with either one or more othersuch parameters, or with a preselected calibration or monitoring signal.

It is another feature of the present invention to provide means andmethod for generating a fixed audio frequency tone signal and forinterrupting such signal at a frequency functionally representative of apreselected physiological parameter.

It is also a feature of the present invention to provide means andmethod for making an audible comparison of the rate of occurrence ofhuman brain waves with a preselected rate of occurrence.

It is also a feature of the present invention to provide means andmethod for generating an audible tone signal having a frequencycharacteristic related to the frequency of human brain waves and tocompare such tone signal with another-tone signal having a preselectedfrequency characteristic.

It is a further feature of this invention to generate a tone'signal, tointerrupt such signal as a function of measured human brain waves, andto compare such signal with a calibration signal which is interrupted ata fixed preselected rate of occurrence.

It is another feature of the invention to generate an audible tonesignal of one pitch and with interruptions at a rate corresponding tothe frequency of human brain waves and to compare such signal with anaudible calibration signal of a different pitch and having interruptionsat a preselected frequency.

It is a further feature of the present invention to compare an audibleindication of human brain wave frequency with an audible calibrationsignal of a preselected frequency and to suppress such signals wheneverthey approach or attain frequency coincidence.

It is also a feature of the present invention to generate a firstaudible tone signal of one pitch interrupted sequentially as a functionof the brain wave frequency of a subject, to simultaneously generate asecond audible tone signal of another pitch interrupted sequentially asa function of another parameter such as skin resistivity, and tosuppress both tone signals upon coincidence of their rates ofinterruption.

These and other features and advantages of the present invention willbecome apparent from the following detailed description, whereinreference is made to the figures in the accompanying drawings.

In the Drawings FIG. 1 is a simplified functional diagram of one form ofapparatus embodying and suitable for practicing the concepts of thepresent invention;

FIG. 2 is a simplified schematic diagram of a portion of the apparatusdepicted more generally in FIG. 1;

FIG. 3 is a simplified schematic diagram of another different portion ofthe apparatus depicted more generally in FIG. 1;

FIG. 4 is a simplified schematic diagram of a further different portionof the apparatus depicted more generally in FIG. 1;

FIG. 5 is a simplified diagrammatic representation of the wave forms ofvarious signals occurring at selected locations throughout the apparatusdepicted in FIGS. 1-4; and

FIG. 6 is a more detailed schematic diagram of a preferred embodiment ofportions of the apparatus depicted in FIGS. 1 and 4.

Detailed Description Referring now to FIG. 1, there may be seen asimplified functional representation of a system embodying the conceptsof the present invention and basically composed of a monitoring sectionfor producing an audible indication of a persons brain wave frequency,and a calibration section for correlatively producing an audibleindication of the brain wave frequency sought to be attained by suchperson. As further indicated in FIG. 1, the system may also include athird section for producing a correlative and preferably audibleindication of a selected physiological feature of the subject person,such as heart beat, breathing rate, body temperature, skin resistivityor the like.

In particular, the monitoring section may include a suitable brain wavesensor 24 such as that depicted in US. Pat. No. 3,658,054, forgenerating an output signal A which is representative in configurationand frequency of the brain waves produced by the subject person. Sincethe amplitude of signal A is extremely low, it is preferably applied toa conventional amplifier 2 which, in turn, produces a functionallyrelated output signal B of suitable amplitude.

As hereinbefore indicated, the electrode or sensor 24 operates to detectand conduct brain wave signals emitted by the subject. Signals emanatingfrom the brain are quite small in amplitude, and thus the sensor outputsig- 6 nal A, and also the amplified signal B, will often include otherunwanted pulses originating from sources in the vicinity or noise in thecircuits represented in FIG. 1. Accordingly, signal B is preferablyapplied to a suitable filter circuit 3 for producing an output signal Cwhich is an amplified representation of the subjects brain waves, butwhich is also substantially free of spurious indications.

In some applications of the technique hereinbefore discussed, it ispreferred that an audible representation of the subjects brain wavecharacteristics be provided only when the subject attains the Alphalevel. Accordingly, the filter 3 may be a low-pass circuit adapted topass only signals having a frequency less than 14 cps or some otherpreselected level.

Referring again to FIG. 1, it may be seen that output signal C may beapplied to one of the two input terminals of a suitable selector switch25 having its output terminal coupled to the input of a triggeredoscillator 6 and also to the input of a wave reshaping circuit 4 ofsuitable design. The purpose of the triggered oscillator is preferablyto generage a constant tone signal of a predetermined audible pitch inresponse to either the positive or negative portion of each undulationin signal C. Accordingly, it may be seen in FIG. 5 that the outputsignal F, which may be coupled to a suitable speaker circuit 7, iscomposed of a sequence of discrete tone signals which occur infunctional response to each brain wave signal emitted by the subjectperson and conveyed by the sensor 24 (unless eliminated by the filtercircuit 3).

Referring again to FIG. 1, it may be seen that the calibration sectionof the depicted apparatus may include a suitable pacing or clock circuit9 for generating a sinusoidal signal B corresponding in frequency to thebrain wave frequency sought to be attained by the subject person.Accordingly, the clock circuit 9 may be a variable oscillator of anyconventional design which includes means for adjusting the frequency ofits output as desired. Since the signal B may be produced without theincorporation of noise or any of the other spurious indicationshereinbefore mentioned, it may be applied without filtering directly tothe input of a second triggered oscillator 8, and also to the input of asecond wave reshaping circuit 10, in the same manner as here inbeforeexplained with respect to signal C. Thus, the output signal F from thesecond triggered oscillator 8 will be similar in configuration to theother output signal F.

It is a preferred feature of the present invention to apply both signalsF and F to the same speaker circuit 7, rather than to separate speakercomponents as in the case of the prior art. As hereinbefore stated,however, it is preferable that F and F be audibly distinguishable fromeach other, and thus it is preferable that the tone of F besignificantly different from the tone of F.

Referring again to FIG. 1, it may further be seen that the system mayalso include a third section for measuring and indicating a selectedphysiological characteristic of the subject person. Accordingly, theremay be included a second sensor 26 which may be a simplepsychogalvanometer such as the Lie Detector Model 28-182 which ismanufactured by Allied Radio Shack, and which produces a frequencysignal representative of the skin resistivity of the subject. Thisoutput signal may be applied directly to the speaker circuit 7 toprovide a third distinguishably different tone signal, or it may beconnected to the other input terminal of the se- 7 lector switch 25.Thus, whichever input is selected by the selector switch 25, it will beapplied to the first mentioned triggered oscillator 6 which, in turn,will generate a signal F for application to the speaker circuit 7.

The system will preferably be provided with a suitable power supply 27and a suitable on-off switch 29, whereby power can be selectivelyapplied to the clock circuit 9 and to the other components which eithercompose or functionally relate to the calibration section of the system.Accordingly, the power supply 27 may also be similarly connected througha second onoff switch 28 to the amplifier 2 and the other systemcomponents which either compose or relate to the monitoring section ofthe system, whereby the subject may utilize either or both of these twosections as desired.

It will be seen in FIG. 1 that power may be supplied continuously to thephysiological sensor 26 at all times the system is activated, and thusthe power supply 27 will preferably include suitable on-off means (notdepicted) whereby the entire system may be inactivated whenever desired.Alternatively, the selector switch 25 may be ganged with anotherselector switch (not depicted) which connects power to the sensor 26 andits circuitry whenever the selector switch 25 is positioned to selectthe output of the sensor 26, and which disconnects power to the sensor26 and its circuitry whenever the selector switch 25 is positioned toselect signal C from the low pass filter 3.

As hereinbefore stated, it is a feature of the ideal embodiment of theinvention to provide for suppression of one or both of the two signals Fand F whenever the actual brain wave frequency of the subject approachesor reaches the Alpha range (or some other predetermined frequency).Accordingly, the system may include the two wave reshaping circuits 4and 10 which may be of any suitable design, but which are preferably ofa design for translating a sine-type wave form into a square wave pulse.Even so, most circuits of this type which are of conventional designwill produce waves which are only substantially squarish in shape andwhich have rounded peaks as indicated in FIG. 5. As will hereinafter beapparent, therefore, it is especially desirable that signals be producedfrom signals D and D, respectively, which are of the same uniformamplitude. Accordingly, there is preferably included a conventionalclamping circuit 5 for producing an appropriate square wave frequency Efrom input signal D, and another similar clamping circuit 11 forproducing another square wave frequency E from input signal D and equalin amplitude to frequency E.

Referring again to FIG. 1, it may be seen that the two square wavefrequencies E and E may be applied to the inputs of an appropriatefrequency differential comparator 12. Thus, the output signal G may beseen in FIG. 8 to be composed of a train of square pulses of a polarityand frequency indicative of the difference between the signals E and E.In other words, the frequency of the pulses in signal G will berepresentative of the frequency differential between signals E and E,

and the polarity of the pulses in signal G will indicate whether thefrequency of signal E is greater or less than the frequency of signal E.

Referring again to FIG. 1, it will be seen that the out put signal Gfrom the comparator 12 is applied to a sampling resistor which,-in turn,is connected to the input of a suitable converter circuit 16 adapted topro duce an output signal K composed of square pulses of either positiveor negative polarity for each input pulse it receives from thecomparator 12. More particularly, the converter 16 produces a zerooutput in response to a positive input, a positive output in response toa zero input, and a positive output in response to a negative input.Accordingly, there is preferably provided a suitable converterdeterminant circuit 13 and one-way switch 14 to eliminate the unwantedpropensity of the converter 16 to produce a positive signal K wheneverthe output signal G from the comparator 12 is negative. Thus, and aswill hereinafter be explained in detail, the converter determinantcircuit 13 is preferably arranged and adapted to generate an outputsignal H which is composed of a negative pulse for each positive pulsein signal G, a positive pulse for each negative pulse in signal G, and azero output whenever the output of the comparator 12 is zero. Signal His applied to the input of a suitable one-way switch 14, however, whichpasses only positive inputs. As illustrated in FIG. 5, the output signalJ from the one-way switch 14 will be composed of a positive pulse foreach negative pulse in signal G, whereby the only pulses reaching theinput of the converter circuit 16 will be the positive pulses in signalG, or the positive pulses of signal J.

It should be noted that what is eventually desired for present purposesis to produce a DC signal suitable for performing a gating function.Hence, the square pulses in signal K are preferably applied to ademodulator circuit l7 suitable for generating an output signal L ofbetter configuration. As illustrated in FIG. 5, however, output signal Lis clearly not of gating configuration, and thus signal L may then beapplied to conventional integrating circuit 18 to produce an outputsignal M which is better suited to actuate a gate 19 which may either bea conventional monostable multivibrator or univibrator circuit. Thus,whenever the univibrator circuit 19 is triggered by an input signal M,it generates an output gating signal N as indicated in FIG. 5, and thissignal N may be applied to the inputs of a pair of suitable muteswitches 21 and 20 having their outputs P and P connected, respectively,to inactivate or paralyze the two triggered oscillators 8 and 6. Inaddition, the gating signal N may for present purposes also beconveniently connected to control the operation of another auxiliaryapparatus such as a tape player 22 or the like.

As hereinbefore stated, the gate 19 may be either a monostablemultivibrator or a univibrator. Accordingly, when a gating signal N isproduced, it may either continue until input signal M disappears, orelse the gating signal N may continue for a preselected time interval asindicated in FIG. 5. In either case, muting signals P and P willcontinue only so long as the mute switches 21 and 20 are actuated.

Referring now to FIG. 2, there may be seen a simplified schematicrepresentation of the converter determinant circuit 13 and one-wayswitch 14 depicted generally in FIG. 1, wherein the determinant circuit13 may include a conventional potentiometer 31 having its windingconnected between signal G and ground or reference potential, andfurther having its wiper portion connected serially with a suitableisolation resistor 32 and one input of an operational amplifier 36having its output connected to produce signal H. The purpose of thepotentiometer 31 is to provide means for establishing a suitable levelfor signal H, and thus the function of the resistor 32 is to prevent anunstable condition from occurring with respect to the amplifier 36whenever the wiper of the potentiometer 31 is turned to ground orreference voltage. In addition, however, the isolation resistor 32 willalso prevent excessive loading on the comparator 12 and other circuitsupstream whenever the wiper of the potentiometer 31 is moved too far inthe opposite direction.

Referring again to FIG. 2, it will be seen that the other input to theamplifier 36 is preferably coupled to ground or reference by way of aresistance 35 having a value such that the voltage of the output signalI-I will be zero whenever the magnitude of the input signal G is zerovoltage. In addition, an additional resistor 34 of suitable value ispreferably interconnected between the output and one of the inputs ofthe amplifier 36, to establish a proper gain for this component, and acapacitance 33 is preferably connected in parallel with the resistor 34for purposes of integration.

The one-way switch 14 depicted in FIG. 1 may, as indicated in FIG. 2,include a conventional diode 37 having its input coupled to receivesignal H from the output of the amplifier 36, and having its outputconnected to one end of a suitable resistor 38. The other end of theresistor 38 constitutes the output of the one-way switch 14. Hence, itwill be apparent that the resistance 30 depicted in FIG. 2 willcorrespond to the sampling resistor illustrated in FIG. 1. In addition,however, an additional resistance 39 may also be provided for furtherestablishing the value of signal J as indicated in FIG. 2. In referenceto FIG. 1, tape deck 22 is shown as a means to provide conditioning, forexample, language learning. The tape deck 22 is energized simultaneouslywhen the mute switches and 21 inactivate the triggered oscillators 6 and8, as hereinbefore explained.

Referring now to FIG. 3, there may be seen a more detailed schematicrepresentation of the speaker circuit 7 which is depicted only generallyin FIG. 1, wherein the output signals F and F from the two triggeredoscillators 6 and 8 may be suitably connected to the primary windings ofsuitable step-down transformers 41 and 42, respectively. Accordingly,the secondary winding of the first transformer 41 is preferablyconnected at one end to one input of a suitable dynamic speaker 45, andat the other end to a load resistor 44 of suitable value and connected,in turn, to the other input of the speaker 45. Similarly, the secondarywinding of the second transformer 42 has one end coupled to one input ofthe speaker 45, and has its other end coupled through another loadresistor 43 of suitable value to the other side of the speaker 45. Itwill thus be apparent that the function of the resistors 44 and 43 is toisolate input signal F from input signal F, and also to balance thesesignals as they are received by the speaker 45.

Referring now to FIG. 4, there may be seen a more detailed schematicrepresentation of the galvanic skin resistance measurement circuitry 26depicted only generally in FIG. 1. In particular, it may be seen thatthis circuit may include any suitable means for deriving a voltagerepresentative of the skin resistivity of a person, such as a pair ofelectrodes 46 and 47 of a design such that they may be detachablyaffixed to the skin of the person. One contact electrode 46 may becoupled directly to the power supply 27 depicted in FIG. 1, but theother contact electrode 47 is preferably coupled to the junction betweenthe winding of a first potentiometer 50 and the emitter 51 of a suitabletransistor 40 having its collector 52 coupled to the winding of a secondpotentiometer. The base electrode 53 of the transistor 40 is preferablycoupled to the wiper of the first potentiometer 50, which has itswinding coupled between the second contact electrode 47 and the junctionbetween ground or reference voltage and the other end of the winding ofthe second potentiometer 49. As also indicated in FIG. 4, the wiper ofthe second potentiometer 49 is preferably connected to the input of avoltage controlled oscillator 55 of conventional design such as toproduce an output frequency which is preferably below the audio range,and which is functionally related or proportional to the skinresistivity measured between the two electrodes 46 and 47. Accordingly,this sub-audio output frequency is preferably connected to one inputterminal of the selector switch 25, whereby this sub-audio frequency maybe selected for coupling to the input of the first triggered oscillator6 depicted in FIG. 1.

Referring again to FIG. 4, it will be apparent that the resistancebetween the two contact electrodes 46 and 47 will be a function of theskin resistivity of the subject person, and that any change in such skinresistivity will therefore produce a functionally related current changeacross the second potentiometer 49. Any change in the resistance in theemitter circuit 51 produces a corresponding or functionally relatedchange in the current across the winding of the second potentiometer 49,and this, in turn, produces a corresponding or functionally relatedchange in voltage across the potentiometer 50. It is this voltage, ofcourse, which is employed by the triggered oscillator 6 to establish thevalue of its output frequency F, and thus the value of the signal F is afunction of the skin resistivity of the subject person.

It should be noted, however, that the tone of the output signal F fromthe triggered oscillator 6 is of a constant preselected pitch indicativeof the source of the signal as hereinbefore stated. Accordingly, and asindicated in FIG. 5, it is the rate of occurrence of each discretesegment orportion of such tone signal which is representative of theskin resistivity of the subject, rather than the pitch or tone of thesignal. In this respect, it should be noted that the frequency oroccurrence rate of the segments of the signal may be indicated bymaintaining a fixed duration of silence between each segment or toneburst of the signal, and by varying the duration of the tone bursts orsegments accordingly. In the alternative, the tone bursts or segmentsmay all have the same fixed duration, and the periods of silencetherebetween may be varied as desired.

It will be readily apparent that various alternative types of circuitsand components may be used to perform many of the various functionshereinbefore described. For example, circuitry for determining heartbeat, breathing rate, and other physiological phenomena may besubstituted for the galvanic skin resistivity circuit 26, ashereinbefore mentioned. In addition, a conventional arrangement of ANDgates or other such logic circuits may be substituted for theunivibrator or monostable multivibrator employed as the gate 19, andperhaps for the integrator 18 and demodulator 17 as well, Also, it willbe apparent that signals F and F may be used to activate human sensesother than hearing.

Referring now to FIG. 6, there may be seen a schematic diagram ofanother form of monitoring device incorporating the galvanic skinresistivity circuit 26 and other apparatus hereinbefore described andsuitable both independent of or in conjunction with the circuitrydepicted in, FIG. 1. In particular, there may be seen a pair ofthumb-press electrodes '101-102 of conventional design which areconnected through resistances 103104 and 106107, and the winding of apotentiometer 105, to a DC amplifier 108 of suitable design. As will beapparent, it is preferable that the amplifier 108 have a high impedanceinput low impedance output characteristic, and thus this component ofthe circuit is preferably composed of a PNP transistor 109interconnected with the wiper of the potentiometer 105, and an NPNtransistor 110 coupled between resistances 111-113.

Referring again to FIG. 6, there may be seen a functional representationof a voltage controlled oscillator l 14 which, for present purposes, maybe a Model ULN 2046A linear integrated circuit as made and sold bySprague Electric Co., or the like. Since this oscillator 114 iscommercially available on an off-the-shelf basis, its internal detailswill not be further illustrated or discussed except for its fourteenterminals which. in FIG. 6, are indicated by references A through N.Accordingly, it may be seen that terminal J is preferably interconnectedbetween resistances 106 and 107, that terminals C and G are connected toground or refer ence voltage, that terminals B and E are preferablyinterconnected by capacitance 119, and that terminal F is interconnectedthrough the resistance 115 to the junction between the capacitance 119and resistance 117 which, in turn, is interconnected to the junctionbetween the grounded electrode 101 and resistance 103.

Referring again to the oscillator 114, it may be seen that terminal D isinterconnected with the junction between resistance 112 and acapacitance 120 which, in turn, has its opposite side coupled betweenterminal A and the junction between resistances 111 and 113. Terminals Kand I are interconnected through resistance 122, and terminals LN arenot connected. However, terminal I is also connected by a capacitance121 to the grounded thumb-press electrode 101.

Referring again to FIG. 6, there may be seen a schematic representationof a suitable transformer 130 having its output winding interconnectedwith a suitable audio speaker 131 which, for present purposes, is adynamic-permanent magnet type component. It is also preferable forpresent purposes to provide for means whereby the output volume of thespeaker 131 may be controlled to a limited extent. Accordingly, aloudsoft switch 135 and resistance 118 is also preferably connectedbetween the output winding of the transformer 130 and the inputterminals of the speaker 131.

Power may be obtained from any suitable source such as the power supply134 interconnected between the grounded electrode 101 and a suitableon-off switch 133 which, in turn, is coupled to the junction betweenterminal K of the oscillator 114 and the input winding of thetransformer 130. Accordingly, a suitable capacitance 132 is preferablycoupled between the junction between the switch 133 and the inputwinding of the transformer 130, and the junction between the powersupply 134 and the grounded electrode 101.

Referring again to FIG. 6, it may be seen that terminal H of theoscillator 114 is coupled through resistances 123 and 124 to the base ofa PNP transistor 125 I having its emitter connected to the junctionbetween the resistance 122 and the input winding of the transformer 130.Accordingly, the collector of transistor 125 is connected throughanother resistance 127 to the base of an NPN transistor 129 having itsemitter connected to the junction between the capacitance 121 and thegrounded electrode 101, and having its collector interconnected betweenthe input winding of the transformer 130 and a capacitance 128 which, inturn, has its opposite side connected to the junction betweenresistances 123 and 124. A further capacitance 126 is preferably coupledin parallel across the resistance 127.

Referring in general to the circuitry represented in FIG. 6, it will'beapparent that what is depicted is an independently arranged andoperating version of the galvanic skin resistivity circuit 26, triggeredoscillator 6 and speaker circuit 7 depicted generally in FIG. 1. Moreparticularly, the transistors 109 and 110, and their associatedcomponents function as the amplifier 26 illustrated in FIG. 4, thevoltage controlled oscillator 114 and its associated components may beequated to the VCO 55 depicted in FIG. 4, and the speaker 131 isfunctionally equivalent to the speaker 45 depicted in FIG. 3. Thus, thecircuitry represented in FIG. 6 provides a train of discrete bursts ofan audible tone signal, wherein the tone frequency or pitch of theaudible is fixed at a preselected level, but wherein the rate ofoccurrence of these discrete bursts of audible tone signal are afunction of the skin resistivity of the subject person contacting thetwo thumb-press electrodes 101 and 102.

As hereinbefore stated, the circuitry depicted in FIG. 6 may be usedeither independently or in conjunction with one or more of the othercircuits depicted functionally in FIG. 1. Furthermore, it may be used todevelop an audible indication of many parameters other than skinresistivity, provided that suitable detection means are substituted forthe electrodes 101 and 102 which are capable of generating anappropriate voltage representative of the magnitude of the parametersought to be measured.

Many other variations and modifications will readily become apparent tothose having experience with circuitry of the type depicted anddescribed herein. Accordingly, it should be clearly understood that thestructures and techniques described herein and. depicted in theaccompanying drawings are illustrative only and are not intended aslimitations on the scope of the present invention.

What is claimed is:

1. A system for monitoring a variable human physiological parameter andthe like, comprising detection means for deriving an electrical signalrepresentative of a parameter sought to be monitored,

voltage means for deriving from said signal a voltage having anamplitude functionally related to a characteristic of said parametersought to be monitored,

a tone signal generator for providing a sequence of discrete incrementsof tone signal each having a duration and rate of occurrencefunctionally related to the amplitude of said voltage, and

, audio means responsive to said increments of tone signal.

2. The system described in claim 1, wherein said tone signal fromsaid-generator has a preselected fixed pitch which is within the audiofrequency range.

3. The system described in claim 2, wherein said voltage means includesan amplifier with a substantially linear amplification characteristicfor amplifying said voltage.

13 4. The system described in claim 3, wherein said amplifier ischaracterized by a high impedance input and a low impedance output.

5. The system described in claim 4, wherein said audio means includes adynamic-permanent magnet type audio speaker means responsive to saidtone signal generator, and volume control means interconnected with saidaudio speaker means. 6. A system for monitoring the skin resistivity ofa selected human subject and the like, comprising a pair of spaced-apartelectrodes for developing a measurement voltage functionally related tothe skin resistivity of said selected subject, an amplifier having ahigh impedance input and low impedance output characteristic foramplifying said measurement voltage in a substantially linear manner, avoltage-controlled oscillator for providing a se- 14 a dynamic-permanentmagnet type audio speaker for providing an indication of said discretebursts of tone signal audible to said selected subject. 7. A method ofmonitoring a variable human physiological parameter and the like,comprising deriving an electrical signal representative of a parametersought to be monitored, deriving from said signal a voltage having anamplitude functionally related to a selected characteristic of saidparameter sought to be monitored, deriving a sequence of discrete burstsof tone signal each having a duration and rate of occurrencefunctionally related to the amplitude of said voltage, and deriving anaudible indication of said bursts of tone signal. 8. The methoddescribed in claim 7, further including deriving said tone signal at afixed preselected pitch quence of discrete bursts of tone signal havinga Within the audio frequency rangefixed pitch within the audio frequencyrange and at a rate of occurrence which is functionally related to themagnitude of said amplified measurement voltage, and

9. The method described in claim 8, further including amplifying in asubstantially linear manner said voltage which is derived from saidelectrical signal.

1. A system for monitoring a variable human physiological parameter andthe like, comprising detection means for deriving an electrical signalrepresentative of a parameter sought to be monitored, voltage means forderiving from said signal a voltage having an amplitude functionallyrelated to a characteristic of said parameter sought to be monitored, atone signal generator for providing a sequence of discrete increments oftone signal each having a duration and rate of occurrence functionallyrelated to the amplitude of said voltage, and audio means responsive tosaid increments of tone signal.
 2. The system described in claim 1,wherein said tone signal from said generator has a preselected fixedpitch which is within the audio frequency range.
 3. The system describedin claim 2, wherein said voltage means includes an amplifier with asubstantially linear amplification characteristic for amplifying saidvoltage.
 4. The system described in claim 3, wherein said amplifier ischaracterized by a high impedance input and a low impedance output. 5.The system described in claim 4, wherein said audio means includes adynamic-permanent magnet type audio speaker means responsive to saidtone signal generator, and volume control means interconnected with saidaudio speaker means.
 6. A system for monitoring the skin resistivity ofa selected human subject and the like, comprising a pair of spaced-apartelectrodes for developing a measurement voltage functionally related tothe skin resistivity of said selected subject, an amplifier having ahigh impedance input and low impedance output characteristic foramplifying said measurement voltage in a substantially linear manner, avoltage-controlled oscillator for providing a sequence of discretebursts of tone signal having a fixed pitch within the audio frequencyrange and at a rate of occurrence which is functionally related to themagnitude of said amplified measurement voltage, and a dynamic-permanentmagnet type audio speaker for providing an indication of said discretebursts of tone signal audible to said selected subject.
 7. A method ofmonitoring a variable human physiological parameter and the like,comprising deriving an electrical signal representative of a parametersought to be monitored, deriving from said signal a voltage having anamplitude functionally related to a selected characteristic of saidparameter sought to be monitored, deriving a sequence of discrete burstsof tone signal each having a duration and rate of occurrencefunctionally related to the amplitude of said voltage, and deriving anaudible indication of said bursts of tone signal.
 8. The methoddescribed in claim 7, further including deriving said tone signal at afixed preselected pitch within the audio frequency range.
 9. The methoddescribed in claim 8, further including amplifying in a substantiallylinear manner said voltage which is derived from said electrical signal.